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Old 11-15-2015, 07:20 PM   #1
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Bow or stern down?

A buddy and I are debating underwater freefall in general and the El Faro in particular.

He says all sinking ships go down nose first.
He believes even if it starts stern down the bow will drop off and overtake because of the resistance to the stern.

I say it would depend on the weight of/in the stern vs. bow and the depth of fall.

Anyone here with real knowledge, math or physics to support either side?
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Old 11-15-2015, 07:30 PM   #2
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Now there's a first world problem.... No idea. Gut feeling says, all accidents are different. (They are in my business) So no clear cut conclusions. Sorry.
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Old 11-15-2015, 07:37 PM   #3
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Watch a bunch of WWII movies of torpedo hits...seems pretty well divided....

But they also involve hull damage...

What parameters are you looking for?
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Old 11-15-2015, 08:02 PM   #4
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Watch a bunch of WWII movies of torpedo hits...seems pretty well divided....

But they also involve hull damage...

What parameters are you looking for?
Gonna be hard to duplicate that...... I mean, I was offered a sub for sale when the curtain came down, but finding torpedoes.... that's another thing. Don't think Cabelas carries those.
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Old 11-15-2015, 08:33 PM   #5
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Quote:
Originally Posted by Hawgwash View Post
A buddy and I are debating underwater freefall in general and the El Faro in particular.

He says all sinking ships go down nose first.
He believes even if it starts stern down the bow will drop off and overtake because of the resistance to the stern.

I say it would depend on the weight of/in the stern vs. bow and the depth of fall.

Anyone here with real knowledge, math or physics to support either side?
Are you assuming they go down keel down and land right side up? A lot don't. Ballast and cargo often shift in the sinking process. Most ships will strike the bottom before developing a sinking trajectory until the bottom is in the thousands of feet.

Interesting story: One of the WWII casualties we looked for was the SS William Rockefeller, one of the largest takers of that era. It was sunk off Hatteras NC. A survivor report from the National Archives indicated that the 572' tanker went vertical as she sank, picking up speed and disappearing like dropping a length of steel pipe vertically in the ocean. Since the tanker didn't stop from striking the ocean floor before disappearing from the surface, it was pointless to keep looking for it as it rested in over 500' of water (far to deep to dive back in the early '80s).

Ted
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Old 11-15-2015, 10:50 PM   #6
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Quote:
Originally Posted by psneeld
What parameters are you looking for?
No real parameters, just need to prove him wrong.
He simply insists ALL sinkers turn bow down, with nothing more to go on than a bunch of WW II movies and concept of the bow being the point of least resistance.

I say, especially an the case of El Faro, if she had a belly full of vehicles and if she started stern down,they could easily have all jammed up in the in the stern and it could have been like a brick in a sock and taken her all the way stern first.

So, I just hoping someone here is a grad of the Maritime Academy of Hacky Sack, Morlacco and can help me win the case of beer.
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Old 11-16-2015, 01:02 AM   #7
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Remember Galileo and the Tower of Pisa. Everything falls at the same rate regardless of mass.

Why don't a feather and a marble fall at the same rate? Wind resistance.

So my theory is that, once a ship loses all bouyancy, it will descend pointy end down, if it doesn't break up. Many shipwrecks are found in pieces on the ocean floor, indicating that breaking up is common, probably due to differing bouyancy along the ship as different sections fill with water at different times.
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Old 11-16-2015, 01:54 AM   #8
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Also, trapped air is likely common making a buoyancy issue that may play into it.
Especially commercial boats with water tight compartments.
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Old 11-16-2015, 04:48 AM   #9
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Jury is still out here.
After extensive tank testing I've decided the yellow end sinks first.
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Old 11-16-2015, 06:38 AM   #10
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Quote:
Originally Posted by Hawgwash View Post
No real parameters, just need to prove him wrong.
He simply insists ALL sinkers turn bow down, with nothing more to go on than a bunch of WW II movies and concept of the bow being the point of least resistance.
If he's talking about WWII Hollywood movies, weren't most of those "sinkings" staged in a pool or a tank?
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Old 11-16-2015, 07:02 AM   #11
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If he's talking about WWII Hollywood movies, weren't most of those "sinkings" staged in a pool or a tank?
Actually many of the WWII Sub casualties were slow to sink, measured in hours to days. Those that were within 50 miles of the coastal USA were sometimes photographed by reconnaissance planes doing coastal patrol. Lots of amazing pictures of ships sinking from WWII in the National Archives.

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Old 11-16-2015, 07:59 AM   #12
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Remember the machinery spaces are generally near the stern. More dense than the crew quarters, hold, depending on cargo. In air, it doesn't matter but in water, more dense sinks faster than less dense. So tell you're buddy it depends on the ships outfitting. I've sunk plenty of model boats in the bathtub and have a master's degree in oceanography to back it up, haha
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Old 11-16-2015, 11:49 AM   #13
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I would think there would be many variables.
Did the water come in fast or slow and where in the hull did it come in? What was the CG when it sank and was there heavy stuff that could move around?
If a ship was heavy aft and was hit by a torpedo aft I'd put my money on stern first. Many probably do sink bow first because they hit something like a rock and filled w water at the bow and .......
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Old 11-16-2015, 12:14 PM   #14
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I checked with King Neptune. Stern first due to the weight in the stern.


Straight from the horse's mouth!


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Old 11-16-2015, 08:04 PM   #15
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If a tree falls in the forest, which way does it fall? Time to change the bong water.
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Old 11-16-2015, 08:16 PM   #16
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If a tree falls in the forest, which way does it fall? Time to change the bong water.
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Old 11-16-2015, 10:01 PM   #17
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Because the engine is the heavy end of a large vessel, with few exceptions, they always sink stern first with the bow being the last to go under.
Case in point. Yogi.
http://youtu.be/KZgdrGTkzAY
Cargo ship
http://youtu.be/sjfoyHF901k
Ship sank for reef
http://youtu.be/3EJfjPQJY3E
And some fishing boats go down fast
http://youtu.be/rHIiYovaorc
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Old 11-16-2015, 10:07 PM   #18
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Dave's not here.
That's a toothpick MAN!
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